1. Field of the Invention
The present invention relates to the electrophotographic copying machine having an operational mode such that a toner image formed on a charge retaining member is to be transferred onto a transfer paper, and particularly to the control of a moving member by which the optical exposure scanning of an original is performed.
2. Description of the Prior Art
As is known, in an electrophotographic copying machine, a series of the following processes are performed; an optical exposure scanning of an original is performed by the movement of a document glass plate or an optical system for exposure to light, (hereinafter collectively referred to as a moving member); an electrostatic latent image is formed on a charge retaining member such as a photosensitive drum; then a toner image developed on the charge retaining member is transferred onto a transfer paper.
Meanwhile, in the abovementioned image transfer process, the following processes are performed: a transfer paper is conveyed toward a fixing means by a paper conveyance means on the one hand; and at the ame time a toner image is transferred onto another portion of said transfer paper which is facing opposite to a charge retaining member on the other hand, therefore, the transfer paper is in an extremely unstable state, and if any shock is given to the machine frame or to the transfer paper, the charge retaining member and the transfer paper being transfer processed are caused to deviate from the correlatively proper positions thereof, that is, the so-called "jittering" is caused. In a phenomena of this kind, both the charge retaining member and the image transferred portion of the transfer paper are heavily shocked by the coincidence of the time when the front end of a transfer paper collides with the guide plate of a fixing means or a fixing roller, at the time when the return movement of a moving member having a large inertia is commenced, and thus the image quality especially in the said image transferred portion is lowered seriously.
So far, to overcome the said shortcoming, the distance of reciprocation of the moving member has been specifically determined and the length of a paper conveyance means has been fixed so that the aforesaid times dot not coincide with each other. However, with the countermeasures of this sort, it is impossible to change the strokes of a moving member according to copy sizes, and an idling time has to be provided, and the time required for a continuous copying becomes longer when a small sized original is applied, or when a variable magnification is required for copying.